982 |
|
* If a whenComplete action throws an exception when triggered by |
983 |
|
* a normal completion, it completes exceptionally |
984 |
|
*/ |
985 |
< |
public void testWhenComplete_actionFailed() { |
985 |
> |
public void testWhenComplete_sourceCompletedNormallyActionFailed() { |
986 |
|
for (boolean createIncomplete : new boolean[] { true, false }) |
987 |
|
for (ExecutionMode m : ExecutionMode.values()) |
988 |
|
for (Integer v1 : new Integer[] { 1, null }) |
1010 |
|
/** |
1011 |
|
* If a whenComplete action throws an exception when triggered by |
1012 |
|
* a source completion that also throws an exception, the source |
1013 |
< |
* exception takes precedence. |
1013 |
> |
* exception takes precedence (unlike handle) |
1014 |
|
*/ |
1015 |
< |
public void testWhenComplete_actionFailedSourceFailed() { |
1015 |
> |
public void testWhenComplete_sourceFailedActionFailed() { |
1016 |
|
for (boolean createIncomplete : new boolean[] { true, false }) |
1017 |
|
for (ExecutionMode m : ExecutionMode.values()) |
1018 |
|
{ |
1125 |
|
}} |
1126 |
|
|
1127 |
|
/** |
1128 |
< |
* handle result completes exceptionally if action does |
1128 |
> |
* If a "handle action" throws an exception when triggered by |
1129 |
> |
* a normal completion, it completes exceptionally |
1130 |
|
*/ |
1131 |
< |
public void testHandle_sourceFailedActionFailed() { |
1131 |
> |
public void testHandle_sourceCompletedNormallyActionFailed() { |
1132 |
|
for (ExecutionMode m : ExecutionMode.values()) |
1133 |
|
for (boolean createIncomplete : new boolean[] { true, false }) |
1134 |
+ |
for (Integer v1 : new Integer[] { 1, null }) |
1135 |
|
{ |
1136 |
|
final CompletableFuture<Integer> f = new CompletableFuture<>(); |
1137 |
|
final AtomicInteger a = new AtomicInteger(0); |
1138 |
< |
final CFException ex1 = new CFException(); |
1139 |
< |
final CFException ex2 = new CFException(); |
1138 |
< |
if (!createIncomplete) f.completeExceptionally(ex1); |
1138 |
> |
final CFException ex = new CFException(); |
1139 |
> |
if (!createIncomplete) assertTrue(f.complete(v1)); |
1140 |
|
final CompletableFuture<Integer> g = m.handle |
1141 |
|
(f, |
1142 |
|
(Integer x, Throwable t) -> { |
1143 |
|
m.checkExecutionMode(); |
1144 |
< |
threadAssertNull(x); |
1145 |
< |
threadAssertSame(ex1, t); |
1144 |
> |
threadAssertSame(x, v1); |
1145 |
> |
threadAssertNull(t); |
1146 |
|
a.getAndIncrement(); |
1147 |
< |
throw ex2; |
1147 |
> |
throw ex; |
1148 |
|
}); |
1149 |
< |
if (createIncomplete) f.completeExceptionally(ex1); |
1149 |
> |
if (createIncomplete) assertTrue(f.complete(v1)); |
1150 |
|
|
1151 |
< |
checkCompletedWithWrappedException(g, ex2); |
1152 |
< |
checkCompletedExceptionally(f, ex1); |
1151 |
> |
checkCompletedWithWrappedException(g, ex); |
1152 |
> |
checkCompletedNormally(f, v1); |
1153 |
|
assertEquals(1, a.get()); |
1154 |
|
}} |
1155 |
|
|
1156 |
< |
public void testHandle_sourceCompletedNormallyActionFailed() { |
1157 |
< |
for (ExecutionMode m : ExecutionMode.values()) |
1156 |
> |
/** |
1157 |
> |
* If a "handle action" throws an exception when triggered by |
1158 |
> |
* a source completion that also throws an exception, the action |
1159 |
> |
* exception takes precedence (unlike whenComplete) |
1160 |
> |
*/ |
1161 |
> |
public void testHandle_sourceFailedActionFailed() { |
1162 |
|
for (boolean createIncomplete : new boolean[] { true, false }) |
1163 |
< |
for (Integer v1 : new Integer[] { 1, null }) |
1163 |
> |
for (ExecutionMode m : ExecutionMode.values()) |
1164 |
|
{ |
1160 |
– |
final CompletableFuture<Integer> f = new CompletableFuture<>(); |
1165 |
|
final AtomicInteger a = new AtomicInteger(0); |
1166 |
< |
final CFException ex = new CFException(); |
1167 |
< |
if (!createIncomplete) assertTrue(f.complete(v1)); |
1166 |
> |
final CFException ex1 = new CFException(); |
1167 |
> |
final CFException ex2 = new CFException(); |
1168 |
> |
final CompletableFuture<Integer> f = new CompletableFuture<>(); |
1169 |
> |
|
1170 |
> |
if (!createIncomplete) f.completeExceptionally(ex1); |
1171 |
|
final CompletableFuture<Integer> g = m.handle |
1172 |
|
(f, |
1173 |
|
(Integer x, Throwable t) -> { |
1174 |
|
m.checkExecutionMode(); |
1175 |
< |
threadAssertSame(x, v1); |
1176 |
< |
threadAssertNull(t); |
1175 |
> |
threadAssertNull(x); |
1176 |
> |
threadAssertSame(ex1, t); |
1177 |
|
a.getAndIncrement(); |
1178 |
< |
throw ex; |
1178 |
> |
throw ex2; |
1179 |
|
}); |
1180 |
< |
if (createIncomplete) assertTrue(f.complete(v1)); |
1180 |
> |
if (createIncomplete) f.completeExceptionally(ex1); |
1181 |
|
|
1182 |
< |
checkCompletedWithWrappedException(g, ex); |
1183 |
< |
checkCompletedNormally(f, v1); |
1182 |
> |
checkCompletedWithWrappedException(g, ex2); |
1183 |
> |
checkCompletedExceptionally(f, ex1); |
1184 |
|
assertEquals(1, a.get()); |
1185 |
|
}} |
1186 |
|
|
3771 |
|
} |
3772 |
|
|
3773 |
|
static class Monad { |
3774 |
< |
static class MonadError extends Error { |
3775 |
< |
public MonadError() { super("monadic zero"); } |
3774 |
> |
static class ZeroException extends RuntimeException { |
3775 |
> |
public ZeroException() { super("monadic zero"); } |
3776 |
|
} |
3777 |
|
// "return", "unit" |
3778 |
|
static <T> CompletableFuture<T> unit(T value) { |
3779 |
|
return completedFuture(value); |
3780 |
|
} |
3781 |
|
// monadic zero ? |
3782 |
< |
static <T> CompletableFuture<T> zero(T value) { |
3783 |
< |
return failedFuture(new MonadError()); |
3782 |
> |
static <T> CompletableFuture<T> zero() { |
3783 |
> |
return failedFuture(new ZeroException()); |
3784 |
|
} |
3785 |
|
// >=> |
3786 |
|
static <T,U,V> Function<T, CompletableFuture<V>> compose |
3794 |
|
f.getNow(null); |
3795 |
|
throw new AssertionFailedError("should throw"); |
3796 |
|
} catch (CompletionException success) { |
3797 |
< |
assertTrue(success.getCause() instanceof MonadError); |
3797 |
> |
assertTrue(success.getCause() instanceof ZeroException); |
3798 |
|
} |
3799 |
|
} |
3800 |
|
|
3825 |
|
static <T> CompletableFuture<T> plus(CompletableFuture<? extends T> f, |
3826 |
|
CompletableFuture<? extends T> g) { |
3827 |
|
PlusFuture<T> plus = new PlusFuture<T>(); |
3828 |
< |
BiConsumer<T, Throwable> action = (T result, Throwable fail) -> { |
3829 |
< |
if (result != null) { |
3828 |
> |
BiConsumer<T, Throwable> action = (T result, Throwable ex) -> { |
3829 |
> |
if (ex == null) { |
3830 |
|
if (plus.complete(result)) |
3831 |
|
if (plus.firstFailure.get() != null) |
3832 |
|
plus.firstFailure.set(null); |
3833 |
|
} |
3834 |
< |
else if (plus.firstFailure.compareAndSet(null, fail)) { |
3834 |
> |
else if (plus.firstFailure.compareAndSet(null, ex)) { |
3835 |
|
if (plus.isDone()) |
3836 |
|
plus.firstFailure.set(null); |
3837 |
< |
} else { |
3838 |
< |
if (plus.completeExceptionally(fail)) |
3839 |
< |
plus.firstFailure.set(null); |
3837 |
> |
} |
3838 |
> |
else { |
3839 |
> |
// first failure has precedence |
3840 |
> |
Throwable first = plus.firstFailure.getAndSet(null); |
3841 |
> |
|
3842 |
> |
// may fail with "Self-suppression not permitted" |
3843 |
> |
try { first.addSuppressed(ex); } |
3844 |
> |
catch (Exception ignored) {} |
3845 |
> |
|
3846 |
> |
plus.completeExceptionally(first); |
3847 |
|
} |
3848 |
|
}; |
3849 |
|
f.whenComplete(action); |
3857 |
|
* https://en.wikipedia.org/wiki/Monad_(functional_programming)#Additive_monads |
3858 |
|
*/ |
3859 |
|
public void testAdditiveMonad() throws Throwable { |
3860 |
+ |
Function<Long, CompletableFuture<Long>> unit = Monad::unit; |
3861 |
+ |
CompletableFuture<Long> zero = Monad.zero(); |
3862 |
+ |
|
3863 |
|
// Some mutually non-commutative functions |
3864 |
|
Function<Long, CompletableFuture<Long>> triple |
3865 |
< |
= (x) -> completedFuture(3 * x); |
3865 |
> |
= (x) -> Monad.unit(3 * x); |
3866 |
|
Function<Long, CompletableFuture<Long>> inc |
3867 |
< |
= (x) -> completedFuture(x + 1); |
3851 |
< |
|
3852 |
< |
Function<Long, CompletableFuture<Long>> unit = Monad::unit; |
3853 |
< |
Function<Long, CompletableFuture<Long>> zero = Monad::zero; |
3867 |
> |
= (x) -> Monad.unit(x + 1); |
3868 |
|
|
3869 |
|
// unit is a right identity: m >>= unit === m |
3870 |
< |
Monad.assertFutureEquals( |
3871 |
< |
inc.apply(5L).thenCompose(unit), |
3858 |
< |
inc.apply(5L)); |
3870 |
> |
Monad.assertFutureEquals(inc.apply(5L).thenCompose(unit), |
3871 |
> |
inc.apply(5L)); |
3872 |
|
// unit is a left identity: (unit x) >>= f === f x |
3873 |
< |
Monad.assertFutureEquals( |
3874 |
< |
unit.apply(5L).thenCompose(inc), |
3875 |
< |
inc.apply(5L)); |
3873 |
> |
Monad.assertFutureEquals(unit.apply(5L).thenCompose(inc), |
3874 |
> |
inc.apply(5L)); |
3875 |
> |
|
3876 |
|
// associativity: (m >>= f) >>= g === m >>= ( \x -> (f x >>= g) ) |
3877 |
|
Monad.assertFutureEquals( |
3878 |
|
unit.apply(5L).thenCompose(inc).thenCompose(triple), |
3879 |
|
unit.apply(5L).thenCompose((x) -> inc.apply(x).thenCompose(triple))); |
3880 |
|
|
3881 |
+ |
// The case for CompletableFuture as an additive monad is weaker... |
3882 |
+ |
|
3883 |
|
// zero is a monadic zero |
3884 |
< |
Monad.assertZero(zero.apply(5L)); |
3870 |
< |
// left zero: zero >>= f === zero |
3871 |
< |
Monad.assertZero(zero.apply(5L).thenCompose(inc)); |
3872 |
< |
// right zero: f >>= zero === zero |
3873 |
< |
Monad.assertZero(inc.apply(5L).thenCompose(zero)); |
3884 |
> |
Monad.assertZero(zero); |
3885 |
|
|
3886 |
< |
// inc plus zero === inc |
3887 |
< |
Monad.assertFutureEquals( |
3888 |
< |
inc.apply(5L), |
3889 |
< |
Monad.plus(inc.apply(5L), zero.apply(5L))); |
3890 |
< |
// zero plus inc === inc |
3891 |
< |
Monad.assertFutureEquals( |
3892 |
< |
inc.apply(5L), |
3893 |
< |
Monad.plus(zero.apply(5L), inc.apply(5L))); |
3886 |
> |
// left zero: zero >>= f === zero |
3887 |
> |
Monad.assertZero(zero.thenCompose(inc)); |
3888 |
> |
// right zero: f >>= (\x -> zero) === zero |
3889 |
> |
Monad.assertZero(inc.apply(5L).thenCompose((x) -> zero)); |
3890 |
> |
|
3891 |
> |
// f plus zero === f |
3892 |
> |
Monad.assertFutureEquals(Monad.unit(5L), |
3893 |
> |
Monad.plus(Monad.unit(5L), zero)); |
3894 |
> |
// zero plus f === f |
3895 |
> |
Monad.assertFutureEquals(Monad.unit(5L), |
3896 |
> |
Monad.plus(zero, Monad.unit(5L))); |
3897 |
|
// zero plus zero === zero |
3898 |
< |
Monad.assertZero(Monad.plus(zero.apply(5L), zero.apply(5L))); |
3898 |
> |
Monad.assertZero(Monad.plus(zero, zero)); |
3899 |
|
{ |
3900 |
< |
CompletableFuture<Long> f = Monad.plus(inc.apply(5L), inc.apply(8L)); |
3901 |
< |
assertTrue(f.get() == 6L || f.get() == 9L); |
3900 |
> |
CompletableFuture<Long> f = Monad.plus(Monad.unit(5L), |
3901 |
> |
Monad.unit(8L)); |
3902 |
> |
// non-determinism |
3903 |
> |
assertTrue(f.get() == 5L || f.get() == 8L); |
3904 |
|
} |
3905 |
|
|
3906 |
|
CompletableFuture<Long> godot = new CompletableFuture<>(); |
3907 |
< |
// inc plus godot === inc (doesn't wait for godot) |
3908 |
< |
Monad.assertFutureEquals( |
3909 |
< |
inc.apply(5L), |
3910 |
< |
Monad.plus(inc.apply(5L), godot)); |
3911 |
< |
// godot plus inc === inc (doesn't wait for godot) |
3912 |
< |
Monad.assertFutureEquals( |
3897 |
< |
inc.apply(5L), |
3898 |
< |
Monad.plus(godot, inc.apply(5L))); |
3907 |
> |
// f plus godot === f (doesn't wait for godot) |
3908 |
> |
Monad.assertFutureEquals(Monad.unit(5L), |
3909 |
> |
Monad.plus(Monad.unit(5L), godot)); |
3910 |
> |
// godot plus f === f (doesn't wait for godot) |
3911 |
> |
Monad.assertFutureEquals(Monad.unit(5L), |
3912 |
> |
Monad.plus(godot, Monad.unit(5L))); |
3913 |
|
} |
3914 |
|
|
3915 |
|
// static <U> U join(CompletionStage<U> stage) { |